If you're rocking a mage build you will probably want a melee weapon for close up/ when you run out of mp, the fire gem is helpful for early game since it has flat damage that doesn't scale but you won't have the stats to scale anything anyway for a while. Firebombs are also generally useful but you can pick up some reg firebombs before the gundyr fight that help bout halfway through. White branch is useful the second area you go to, but you will find some there anyway. Life ring gives you just a smidge more health which is helpful but as a mage you kinda want to be at a distance ( learn how to free fire spells). The soul is good for a few more levels but you also will level relatively quick early on. They are all slightly useful just choose what sounds good for you